Exercise intolerance of chronic diseases associated with increased morbidity and mortality, and reduced quality of life for patients. The present study determined pathophysiological mechanisms of exercise intolerance in pulmonary tuberculosis (PT) patients. Methods. In a prospective cross-sectional observational study 95 pulmonary cavitary tuberculosis patients performed cardiopulmonary exercise testing with metabolic, ventilation and haemodynamic measurements. Peak exercise O2 consumption and cardiac performance were measures of exercise tolerance. Results. The physical performance was reduced in all of the examined PT patients, the decrease was severe (less than 60% predicted) in 62.1%. Exercise intolerance was in the majority (89.5 %) patients. Ability to use oxygen (decrease of anaerobic threshold) was diminished in 80.0%, the ventilation efficiency was decreased in 53.7% (the increase in EqCO2 - 53.7%, EqO2 - 35.8%), disorders ofventilation-perfusion relationships (increase VD/VT) was in 51.6%, impairment of O2 delivery (reduced O2-pulse) was in 52.6%, myocardial ischemia was detected only in 2.1%. Conclusions. The leading pathophysiological mechanisms of exercise intolerance in PT patients were of oxygen utilization violation and ventilation inefficiency.